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Journal of Magnesium and Alloys 2022年第2期10卷 434-445页

作者： Yong Chae Lim Jiheon Jun Donovan N.Leonard Yuan Li Jian Chen Michael P.Brady Zhili Feng Materials Science and Technology Division Oak Ridge National LaboratoryOne Bethel Valley RoadOak RidgeTN 37831USA

A new testing methodology was developed to quantitively study galvanic corrosion of AZ31B and thermoset carbon-fiber–reinforced polymer spot-joined by a friction self-piercing riveting ***-defined areas of AZ31B in the joint were exposed in 0.1 M NaCl solution over *** galvanic corrosion of AZ31B was observed as exposure time *** measured volume loss was converted into corrosion current that was at least 48 times greater than the corrosion current of AZ31B without galvanic *** percent of the mechanical joint integrity was retained for corroded F-SPR joints to 200 h and then decreased because of the massive volume loss of AZ31B。

关键词： Multi-material joining Carbon fiber–reinforced polymer AZ31B friction self-piercing riveting Galvanic corrosion Mechanical joint strength

A Comparative Study of friction self-piercing riveting and self-piercing riveting of Aluminum Alloy AA5182-O

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Engineering 2021年第12期7卷 1741-1750页

作者： Yunwu Ma He Shan Sizhe Niu Yongbing Li Zhongqin Lin Ninshu Ma Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan

In this paper,self-piercing riveting(SPR)and friction self-piercing riveting(F-SPR)processes were employed to join aluminum alloy AA5182-O *** studies were carried out to compare the two processes in terms of joint macrogeometry,tooling force,microhardness,quasi-static mechanical performance,and fatigue *** results indicate that the F-SPR process formed both rivet–sheet interlocking and sheet–sheet solid-state bonding,whereas the SPR process only contained rivet–sheet *** the same rivet flaring,the F-SPR process required 63%less tooling force than the SPR process because of the softening effect of frictional heat and the lower rivet hardness of *** decrease in the switch depth of the F-SPR resulted in more hardening of the aluminum alloy surrounding the *** higher hardness of aluminum and formation of solid-state bonding enhanced the F-SPR joint stiffness under lap-shear loading,which contributed to the higher quasi-static lap-shear strength and longer fatigue life compared to those of the SPR joints.

关键词： self-piercing riveting friction self-piercing riveting Mechanical joining Quasi-static strength Fatigue

Mechanical joint performances of friction self-piercing riveted carbon fiber reinforced polymer and AZ31B Mg alloy

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Journal of Magnesium and Alloys 2022年第12期10卷 3367-3379页

作者： Yuan Li Yong Chae Lim Jian Chen Jiheon Jun Zhili Feng Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA

Carbon fiber reinforced polymer(CFRP) and AZ31B Mg alloy were joined by the friction self-piercing riveting(F-SPR) with different steel rivet shank sizes. With the increase of rivet shank size, lap shear fracture load and mechanical interlock distance increased. Ultrafine grains were formed at the joint in AZ31B as a result of dynamic recrystallization, which contributed to the higher hardness. Fatigue life of the CFRP-AZ31B joint was studied at various peak loads of 0.5, 1, 2, and 3 kN and compared with the resistance spot welded AZ31B-AZ31B from the open literature. The fatigue performance was better at higher peak load(>2 kN) and comparable to that of resistance spot welding of AZ31B to AZ31B at lower peak loads(<1 kN). From fractography, the crack initiation for lower peak load(<1 kN) case was observed at the fretting positions on the top and bottom surfaces of AZ31B sheet. When peak load was increased, fretting between the rivet and the top of AZ31B became more dominant to initiate a crack during fatigue testing.

关键词： friction self-piercing riveting Magnesium alloy Carbon fiber reinforced polymer Dynamic recrystallization Fatigue life Crack initiation

Microstructural evolution in friction self-piercing riveted aluminum alloy AA7075-T6 joints

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Journal of Materials Science & Technology 2021年第23期82卷 80-95页

作者： Yunwu Ma Sizhe Niu Huihong Liu Yongbing Li Ninshu Ma Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240PR China State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240PR China Joining and Welding Research Institute Osaka UniversityOsaka567-0047Japan

friction self-piercing riveting(F-SPR)is an emerging technique for low ductility materials joining,which creates a mechanical and solid-state hybrid joint with a semi-hollow *** severe plastic deformation of work materials and localized elevated temperatures during the F-SPR process yield complex and heterogeneous *** cut-off action of the work materials by the rivet further complicates the material flow during joint *** study employed the F-SPR process to join AA7075-T6 aluminum alloy sheets and systematically investigated the microstructural evolutions using electron backscatter diffraction(EBSD)*** results suggested that as the base material approached the rivet,grains were deformed and recrystallized,forming two distinct fine grain zones(FGZs)surrounding the rivet and in the rivet cavity,re s ***-state bonding of aluminum sheets occurred in the *** formation of FGZ outside the rivet is due to dynamic recrystallization(DRX)triggered by the sliding-to-sticking transition at the rivet/sheet *** FGZ in the rivet cavity was caused by the rotation of the trapped aluminum,which created a sticking affected zone at the trapped aluminum/lower sheet interface and led to *** rate gradient in the trapped aluminum drove the further expansion of the sticking affected zone and resulted in grain refinement in a larger span.

关键词： friction self-piercing riveting Semi-hollow rivet Aluminum alloy Affected zone Dynamic recrystallization

Combined strengthening mechanism of solid-state bonding and mechanical interlocking in friction self-piercing riveted AA7075-T6 aluminum alloy joints

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Journal of Materials Science & Technology 2022年第10期105卷 109-121页

作者： Yunwu Ma Bingxin Yang Shanqing Hu He Shan Peihao Geng Yongbing Li Ninshu Ma Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan

A recently developed friction self-piercing riveting(F-SPR)technique based on the combination of fric-tion stir processing and riveting has been reported to possess both solid-state bonding and mechanical fastening ***,there is still a lack of quantitative understanding of the hybrid en-hancement mechanism,hindering its engineering *** fill in this gap,the current research investigated the microstructure evolution,microhardness distribution,and miniature-tensile performance of the aluminum alloy AA7075-T6 F-SPR joints by *** accurate numerical simulation model was established to quantitatively evaluate the individual contributions of microstructure,local bonding strength,and macro interlocking to the performance of the joint,which could well explain the experi-mental *** was found that due to the friction stirring of the rivet,solid-state bonding driven by dynamic recrystallization is realized between the trapped aluminum in the rivet cavity and the bottom aluminum *** solid-state bonding zone has 75%yield strength,81%ultimate tensile strength,and 106%elongation compared to the base *** solid-state bonding enables the internal interlock-ing between the trapped aluminum and the rivet to withstand the additional load,which forms a novel dual-interlock fastening mechanism and increases the peak cross-tension force by 14.3%compared to the single-interlock joint.

关键词： Combined strengthening friction self-piercing riveting Miniature tensile test Solid-state joining Dual-interlocking Numerical simulation

Impact of Stack Orientation on self-piercing Riveted and friction self-piercing Riveted Aluminum Alloy and Magnesium Alloy Joints

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Automotive Innovation 2020年第3期3卷 242-249页

作者： Yunwu Ma Sizhe Niu He Shan Yongbing Li Ninshu Ma Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghaiChina State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghaiChina Joining and Welding Research Institute Osaka UniversityOsakaJapan

self-piercing riveting(SPR)is a mature method to join dissimilar materials in vehicle body *** self-piercing riveting(F-SPR)is a newly developed technology for joining low-ductility materials by combining SPR and friction stir spot welding *** this paper,the SPR and F-SPR were employed to join AA6061-T6 aluminum alloy and AZ31B magnesium *** two processes were studied in parallel to investigate the effects of stack orientation on riveting force,macro-geomet-rical features,hardness distributions,and mechanical performance of the *** results indicate that both processes exhibit a better overall joint quality by riveting from AZ31B to *** cracking in the Mg sheet is produced when riveting from AA6061-T6 to AZ31B in the case of SPR,and the cracking is inhibited with the thermal softening effect by friction heat in the case of *** F-SPR process requires approximately one-third of the riveting forces of the SPR process but exhibits a maximum of 45.4%and 59.1%higher tensile-shear strength for the stack orientation with AZ31B on top of AA6061-T6 and the opposite direction,respectively,than those of the SPR *** stack orientation of riveting from AZ31B to AA6061-T6 renders better cross-section quality and higher tensile-shear strength and is recommended for both processes.

关键词： self-piercing riveting friction self-piercing riveting Aluminum alloy Magnesium alloy Stack orientation